Loss Mitigation Research Articles

Landslide Susceptibility Evaluation Using Different Slope Units Based on BP Neural Network.

Landslides are one of the most widespread natural hazards that cause damage to both property and life every year. Therefore, the landslide susceptibility evaluation is necessary for land hazard assessment and mitigation of landslide-related losses. Selecting an appropriate mapping unit is an essential step for landslide susceptibility evaluation. This study tested the back propagation (BP) neural network technique to develop a landslide susceptibility map in Qingchuan County, Sichuan Province, China. It compared the results of applying six different slope unit scales for landslide susceptibility maps obtained using hydrological analysis. We prepared a dataset comprising 973 historical landslide locations and six conditioning factors (elevation, slope degree, aspect, lithology, distance to fault lines, and distance to drainage network) to construct a geospatial database and divided the data into the training and testing datasets. We based on the BP learning algorithm to generate landslide susceptibility maps using the training dataset. We divided Qingchuan County into six different scales of slope unit: 4,401, 13,146, 39,251, 46,504, 56,570, and 69,013, then calculated the receiver operating characteristic (ROC) curve, and used the area under the curve (AUC) for the quantitative evaluation of 6 different slope unit scales of landslide susceptibility maps using the testing dataset. The verification results indicated that the evaluation generated by 56,570 slope units had the highest accuracy with a ROC curve of 0.9424. Overelaborate and rough division of slope units may not get the best evaluation results, and it is necessary to obtain the slope units most consistent with the actual situation through debugging. The results of this study will be useful for the development of landslide hazard mitigation strategies.

Long-term study on the nitrogen retention potential of bark extracts and a polymer based thereof in cattle manure slurry

The addition of tree bark extracts, commercial tannin powder and a tannin-based polymer to cattle manure was investigated for its influence on the gaseous emission and nitrogen conservation potential for 28 days. In lab trials with ammonia solution as reference, the retention of ammonia was 13%, 40% and up to 65% for untreated solution, spruce bark extract and chestnut tannin respectively. The gaseous emission from manure was reduced by 40%, 58% and 66% for chestnut tannin and spruce bark extract, larch bark extract and the tannin polymer, and oak tannin, respectively. For long-term nitrogen loss mitigation, 20% more nitrogen was preserved when spruce or larch bark extract or oak tannin was added to the manure compared to the reference measurements. A combination of the pH lowering effect of tannins and covalently bonding ammonia to flavonoid hydroxy groups provides a viable method for reduction of nitrogen loss in cattle manure.

Upregulation of Runt related transcription factor 1 (RUNX1) contributes to tendon–bone healing after anterior cruciate ligament reconstruction using bone mesenchymal stem cells

BackgroundAnterior cruciate ligament (ACL) injury could lead to functional impairment along with disabilities. ACL reconstruction often fails owing to the regeneration failure of tendon–bone interface. Herein, we aimed to investigate the effects of Runt related transcription factor 1 (RUNX1) on tendon–bone healing after ACL reconstruction using bone mesenchymal stem cells (BMSCs).MethodsBMSCs were isolated from the marrow cavity of rat femur, followed by the modification of RUNX1 with lentiviral system. Then, an ACL reconstruction model of rats was established with autografts.ResultsResults of flow cytometry exhibited positive-antigen CD44 and CD90, as well as negative-antigen CD34 and CD45 of the BMSCs. Then, we found that RUNX1-upregulated BMSCs elevated the decreased biomechanical strength of the tendon grafts after ACL reconstruction. Moreover, based on the histological observation, upregulation of RUNX1 was linked with better recovery around the bone tunnel, a tighter tendon–bone interface, and more collagen fibers compared to the group of BMSCs infected with LV-NC. Next, RUNX1-upregulated BMSCs promoted osteogenesis after ACL reconstruction, as evidenced by the mitigation of severe loss and erosion of the cartilage and bone in the tibial and femur area, as well as the increased number of osteoblasts identified by the upregulation of alkaline phosphatase, osteocalcin, and osteopontin in the tendon–bone interface.ConclusionElevated expression of RUNX1 contributed to tendon–bone healing after ACL reconstruction using BMSCs.

Butterfly optimizer assisted Max\u2013Min based multi-objective approach for optimal connection of DGs and optimal network reconfiguration of distribution networks

Currently, the electrical distribution system is experiencing challenges such as low system efficiency due to substantial real power losses, a poor voltage profile, and inadequate system loadability as a result of the tremendous increase in system load demand. Therefore, distribution system operators are searching for ways to improve system efficiency and loadability. Distributed Generation technology has attracted a lot of researchers’ interest in recent days because of its enormous technological advantages in dealing with the aforementioned issues. This work presents a Max–Min based multi-objective optimization approach for optimal connection of distributed generators (OCDG) in the presence of optimal distribution network reconfiguration (ODNR) to enhance the system loadability (lambda_{{{text{max}}}}) and to reduce real power loss. Two scenarios are taken to achieve the proposed objectives. Scenario-1 deals with the enhancement of loss mitigation & system loadability. In scenario-2, to extract maximum benefits with less amount of real power injection by DGs into the system, DGs real power injection is taken as one of the objectives. Under each scenario, three cases are investigated. Case 1 and case 2 deal with single-objective optimization, whereas case 3 deals with multi-objective optimization. The butterfly Optimization (BO) technique is implemented for the optimization of proposed objectives. The proposed method is tested on 33 bus, 69 bus radial distribution test systems. To test the potential of the BO algorithm, the outcomes are contrasted with the suitable results that are accessible in the literature. From the outcomes, it was observed that real power loss of the system is reduced to (75–89)%, loadability enhanced to (94–121)% with the injection of 64% KVA by DGs into 33 & 69 bus systems.

Influence of cell edges on the performance of silicon heterojunction solar cells

Full size silicon heterojunction solar cells reach conversion efficiencies above 25%. However, photoluminescence pictures of such cells (full or cut) reveal a significant recombination activity at the cell edges. Therefore, mitigating recombination at the edges can in principle represent an interesting path to unlock higher cell efficiencies. This challenge is all the more important for cells with a high perimeter/area ratio, as achieved through the cutting of full size cells. For such technologies, the edges resulting from cutting are cleaved while the remaining edges typically feature a gap where TCO is missing to avoid front to back short-circuit. In this paper, we specify the physical mechanisms involved in the edge-induced performance losses for SHJ cells. In light of these results, we provide guidelines for the mitigation of such losses at the full-size and cut cells scale for M6 to M12 sizes such as the reduction of the TCO-free region and the c-Si bulk resistivity. Having a closer look at cut cells, we calculate the cell performance as a function of its size (from half-to sixth-cell), the size of its mother cell (from M6 to M12) and the passivation quality of the cut-edges. Our results emphasize on the interest to develop suitable repassivation schemes for cut cells to improve or even surpass the efficiency of the mother cell.

Optimizing 6‐Hydroxydopamine Concentrations for induction of a Parkinson’s Disease Like Behavior in Zebrafish

Parkinson’s disease is an increasing problem that affects the quality of life for over 10 million people worldwide. Affected individuals undergo worsening symptoms that begin with motor function impairment and can eventually result in death. Parkinson’s Disease is associated with the loss of Tyrosine Hydroxylase (TH) expressing dopaminergic neurons. TH is the rate limiting enzyme in catecholamine neurotransmitter synthesis including dopamine. Therefore, chemically induced animal models have focused on mitigation of movement abnormalities and loss of dopaminergic neurons as indicators for drug screening. We chose the 6‐hydroxydopamine (6‐OHDA) chemically induced Parkinson’s Disease model in zebrafish as a tool for drug screening. Previous work on this model had been conducted with varying drug concentrations and methodologies. All demonstrated reductions in TH expressing neurons; however, the behavioral assessments varied in both method, dose of OHDA (1‐750 μM 6OHDA), and whether behavioral abnormalities were observed. The objective of the current study is to determine the minimal 6‐OHDA dosage that is sufficient to induce a significant difference in behavioral effects while minimizing morphological toxicity. Zebrafish larvae were treated daily with 6‐OHDA with ascorbic acid from 2 to 5‐day post fertilization (dpf). We observed significant difference in behavior at ~20 μM 6‐OHDA, and developmental delays in swim bladder formation at 85 μM 6‐OHDA. The swim bladders were developed by 5 dpf when we assessed swim behavior; however, other signs of delay may still be present that would complicate results. Several studies focused on doses of 150 μM 6‐OHDA or higher; however, at these doses we observed severe morphological issues including edema, curved spines, and death. Future work will focus on the TH‐expressing neuron pathology as assessed by immunohistochemical and Western blotting methodologies.

Prioritising food loss and waste mitigation strategies in the fruit and vegetable supply chain: A multi-criteria approach

Although reducing food loss and waste (FLW) is a global concern, there is a scarcity of literature devoted to the selection of suitable mitigation strategies. Previous studies are more focused on the disposal or valorisation of FLW, rather than on its reduction or prevention, and the effectiveness of the mitigation strategies have hardly been evaluated. Therefore, this study develops and presents an evaluation framework to: (1) identify potential mitigation strategies based on the causes of FLW, (2) select criteria to assess the prevention measures of FLW and (3) evaluate and rank mitigation strategies to fight FLW. Fuzzy Step-Wise Weight Assessment Ratio Analysis (SWARA) is employed to determine the relative weights of the evaluation criteria and Fuzzy Weighted Aggregated Sum Product Assessment (WASPAS) is implemented to rank the mitigation strategies for FLW. The evaluation framework is further tested in Portugal in the context of the Fruit and Vegetable Supply Chain (FVSC) and a sensitivity analysis was conducted to assess the robustness of the results. Overall, 16 mitigation strategies (related to information, quality, technology or transport and infrastructure) were selected and considered relevant to tackle the causes of FLW in the Portuguese FVSC. The results show that the higher ranked strategies are the ones most transversal to the FVSC, which highlights the role of collaboration, coordination and information sharing between the stakeholders in the prevention and reduction of FLW. Furthermore, ensuring coordination and close collaboration between stakeholders may also help to implement the technology-related mitigation strategies identified. This paper provides researchers, practitioners and policymakers with a comprehensible and structured approach that can be replicated for any region, supply chain or food product in order to prioritise cost effective mitigation strategies for FLW with more significant environmental and social gains.

Mitigation of High-Frequency Eddy Current Losses in Hairpin Winding Machines

In high-speed and high-frequency electric machines, one of the major issues that impacts the performance and capability of a machine is the high-frequency eddy current losses in the windings. This work deals with AC winding losses in flat rectangular conductors. Aiming for eddy current loss mitigation, two different materials are investigated and compared for the same winding design, namely copper and aluminum. Using the finite element method (FEM), the conductor loss and current density behavior are simulated at the strand level. Further, in order to verify the simulated losses, the AC losses are measured and compared over a wide range of frequencies. Finally, recommendations are provided based on the obtained measurements to identify the best winding topology that is most suitable for automotive applications.

Risk of Carbon Leakage and Border Carbon Adjustments under the Korean Emissions Trading Scheme

Purpose – This paper examines South Korea’s potential status as a carbon leakage country, and the level of risk posed by the Korean emissions trading scheme (ETS) for Korean industries. The economic effects of border carbon adjustments (BCAs) to protect energy-intensive Korean industries in the process of achieving the carbon reduction target by 2030 through the Korean ETS are also analyzed. Design/methodology – First, using the Korean Input–Output (IO) table, this paper calculates the balance of emissions embodied in trade (BEET) and the pollution terms of trade (PTT) to determine Korean industries’ carbon leakage status. Analyses of the risk level posed by carbon reduction policy implementation in international trade are conducted for some sectors by applying the EU criteria. Second, using a computable general equilibrium (CGE) model, three BCA scenarios, exemption regulations (EXE), reimbursement (REB), and tariff reduction (TAR) to protect the energy-intensive industries under the Korean ETS are addressed. Compared to the baseline scenario of achieving carbon reduction targets by 2030, the effects of BCAs on welfare, carbon leakage, outputs, and trading are analyzed. Findings – As Korea’s industrial structure has been transitioning from a carbon importing to a carbon leaking country. The results indicate that some industrial sectors could face the risk of losing international competitiveness due to the Korean ETS. South Korea’s industries are basically exposed to risk of carbon leakage because most industries have a trade intensity higher than 30%. This could be interpreted as disproving vulnerability to carbon leakage. Although the petroleum and coal sector is not in carbon leakage, according to BEET and PTT, the Korean ETS exposes this sector to a high risk of carbon leakage. Non-metallic minerals and iron and steel sectors are also exposed to a high risk of carbon leakage due to the increased burden of carbon reduction costs embodied in the Korean ETS, despite relatively low levels of trade intensity. BCAs are demonstrated to have an influential role in protecting energy-intensive industries while achieving the carbon reduction target by 2030. The EXE scenario has the greatest impact on mitigation of welfare losses and carbon leakage, and the TAF scenario causes a disturbance in the international trade market because of the pricing adjustment system. In reality, the EXE scenario, which implies completely exempting energy-intensive industries, could be difficult to implement due to various practical constraints, such as equity and reduction targets and other industries; therefore, the REB scenario presents the most realistic approach and appears to have an effect that could compensate for the burden of economic activities and emissions regulations in these industries. Originality/value – This paper confirms the vulnerability of the Korean industrial the risk of carbon leakage, demonstrating that some industrial sectors could be exposed to losing international competitiveness by implementing carbon reduction policies such as the Korean ETS. The contribution of this paper is the identification of proposed approaches to protect Korean industries in the process of achieving the 2030 reduction target by analyzing the effects of BCA scenarios using a CGE model.

Rapid Site Selection to Prioritize Coastal Seascapes for Nature-Based Solutions With Multiple Benefits

Coastal seascapes are productive and diverse land-sea systems that provide many valuable benefits yet are increasingly threatened by human activity. Scaling up of nature-based solutions (NbS) to effectively protect, sustainably manage, and restore coastal seascapes is urgently required for mitigation of climate change and biodiversity loss while also providing socio-economic benefits. Evidence-based site selection is an important first step to improve the outcomes and avoid negative impacts when prioritizing NbS investments at national level. We developed a spatially explicit, integrative and culturally relevant ecosystem-based site selection process to identify a portfolio of seascapes for NbS consideration in the United Arab Emirates (UAE). The primary goal was to rank planning units based on potential for climate change mitigation action, positive impact to biodiversity and socio-economic benefits to people. The multi-criteria site-selection framework provided a rapid, transparent, repeatable and scalable tool. The highest weightings were assigned to blue carbon storage value, biodiversity conservation features, and local stakeholder preferred areas. Spatial proxies for benefits to people were represented by population density and accessibility to coastal seascapes, relative tourism and recreation potential, and importance of fish habitat and fishing grounds for food security. Participatory mapping of local knowledge and review of existing data ensured that both qualitative and quantitative criteria were reliable, up-to-date and locally relevant. Two distinct clusters of high suitability planning units were identified in the Abu Dhabi region and four along the north-western coast of the UAE. Most high suitability sites were located outside of existing marine protected areas. Alternative spatial scenarios without stakeholder bias underscored the suitability of sites identified through participatory mapping and highlighted additional priority sites for future scaling-up of NbS. A spatial corridor of medium and high suitability planning units across the region offers potential for designing well-connected NbS investments to accelerate and boost synergistic outcomes and increase resilience. The site selection framework provides a rapid tool that integrates local and global open access data at a range of scales with great potential for transferability to other regions worldwide.

Performance of a Prototype Boom Sprayer for Bed-Grown Carrots Based on Canopy Deposition Optimization, Ground Losses and Spray Drift Potential Mitigation in Semi-Field Conditions

The H2020-project OPTIMA concept of smart sprayer relies on several functionalities, including variable nozzle spacing for bed-grown carrots, based on an air-assisted boom sprayer. A prototype boom was designed and evaluated though canopy deposition, ground losses, and spray drift potential. Four bed spray configurations, including various nozzle types, angles, and sizes (XR8004, combination of AIUB8504/AI11004, AI8004, and XR8002) at the most appropriate nozzle spacing and height, were tested and compared to a broadcast application (XR11004). Deposition measurements were performed on carrots in bins at early and full-grown stages with respective target zone width of 1.4 m and 2.2 m. Spray drift potential measurements were performed following ISO 22401, 2015. The spray boom was equipped with an air sleeve providing different air speeds (0, 4, 8 m s−1). The relative depositions at both growth stages showed a significant effect of spray configuration and lowest values were found for the broadcast application. The configurations consisting of air inclusion nozzles generated the lowest drift potential compared to the broadcast application, although not significantly different. Bed spray configurations can thus improve canopy depositions and spray drift potential compared to a conventional broadcast application when the boom height and the nozzle spacing are adjusted to the growth stage.

Determination of dominant recombination site in perovskite solar cells through illumination‐side‐dependent impedance spectroscopy

AbstractPerovskite solar cells (PSCs) have attracted wide attention due to their capacity to achieve high‐power conversion efficiencies. However, the high trap‐assisted recombination taking place in the active layer leads to performance loss in PSCs. In particular, the excessive recombination at the interface between the perovskite active layer and the carrier selective contacts can be especially problematic. Therefore, the identification of the dominant recombination pathways in a given PSC architecture is of significant importance for the mitigation of losses and enhancement of device performance. Here, we introduce an approach for identifying the dominant recombination pathways in PSCs by applying illumination‐side‐dependent impedance spectroscopy (ISD‐IS) measurements on the devices with a semi‐transparent top electrode. We validate this technique using coupled ionic‐electronic numerical simulations and apply it experimentally on a standard PSC structure. Overall, this approach could be of significant importance for pinpointing the performance bottlenecks in PSC devices under operationally relevant conditions and providing a more detailed picture of the losses in a complete PSC device by examining its behaviors under illumination from both sides at different operation conditions, which could allow for a more targeted optimization strategy of PSCs to improve their performance.

Exploring Systems Thinking Competence of Finns in Fostering Sustainable Transformation

Systems thinking competence is one of the key sustainability competences to make the future more sustainable by focusing on individuals’ capability to analyse sustainability problems across different sectors and scales. The other competencies to foster systems thinking are futures thinking competence, values and critical thinking competence, action-oriented competence, and collaboration competence. In this study, we examined Finnish people’s systems thinking competence and its connections to sustainable transformation. The survey data collected from Finns (n = 2006) were analysed using principal component analysis (PCA) and hierarchical regression analysis. The study showed that the sustainability component loaded reliably into principal components. In particular, the Cronbach’s alpha (0.91) and Spearman–Brown (0.90) were high for systems thinking competence. The hierarchical regression analysis showed that Finns’ values, critical thinking, and individual action-oriented competence predict their systems thinking competence. The results indicate that Finns’ ideas of climate change and biodiversity loss mitigation arise from their individual values and opinions that actions are implemented in an ethically just way.

Localization and Mitigation of Loss in Niobium Superconducting Circuits

Using selective post-fabrication etching, different ratios of TLS and other resonator losses are associated with the silicon and niobium surface oxides, while the resonator coherent lifetime is increased by a factor of five.

Power losses mitigation through electrical reconfiguration in partial shading prone solar PV arrays

The susceptibility of solar photovoltaic (PV) modules towards partial shading is one of the major demerits encountered by PV arrays installed in the field. The partial shading among the modules leads to a serious reduction in the array power generation as it introduces several losses due to mismatch among modules. These power losses are mainly countered by implementing various electrical interconnecting configurations such as bridge-linked (BL), honeycomb (HC), and total-cross-tied (TCT) rather than using the conventional series-parallel (SP) connection. However, the configurations fail to generate maximum power during all partial shading scenarios. Hence, in this paper, a new module electrical reconfiguration technique is proposed to disperse the effect of partial shading power generation improvement and reduce the losses in the PV arrays. The technique is a one-time fixed electrical reconnection strategy for modules based on the algorithm proposed and requires no sensors and switches. The efficacy of the proposed electrical reconfiguration is investigated for two array sizes in MATLAB/Simulink and a real-time experimental environment whereas, the algorithm is programmed in the Python language. Also, a comparison is done with the conventional electrical configurations under various shading scenarios using the characteristics curves analysis, power generation, losses, efficiencies and performance ratio. The proposed reconfiguration enhances the power output of 26.92% than SP, 24.07% than BL, 25.17% than HC, and 22.96% than TCT during shading.

Cavernous Hemangioma of the Cavernous Sinus-Same Pathology, Different Disease: 2-Dimensional Operative Video.

Cavernous sinus cavernous hemangiomas (also known as cavernomas) and intra-axial cavernomas share identical histologic features; however, their epidemiology, clinical behavior, and surgical management are quite different. Cavernous sinus cavernous hemangiomas behave more like neoplasms with progressive growth and mass effect, as opposed to intraparenchymal cerebral cavernomas that present with repeated hemorrhages.1,2 Cavernous sinus cavernous hemangiomas are uncommon benign lesions arising within the cavernous sinus, often extending into the sellar, suprasellar, and middle cranial fossa regions.3,4 Debate continues about their nature as vascular malformations.5 Clinical manifestations typically consist of cranial neuropathies rather than hemorrhagic events. Although radiosurgery was found to be ineffective in treatment of cavernomas,6 radiation7 and radiosurgery8,9 have occasionally been reported to reduce cavernous sinus cavernous hemangioma volume, although these modalities are not curative, and data on long-term control are lacking. Furthermore, the patients are frequently young. Therefore, surgical excision is the preferred treatment10,11 and can be accomplished through a purely extradural approach because the lesion remains enveloped by the dural leaves.3,12,13 Operating extradurally minimizes the risk of injury to the brain parenchyma, allows proximal control of the internal carotid artery, and provides access to the cavernous sinus through the corridors between the cranial nerves. Cavernous sinus cavernous hemangiomas are highly vascular, and proactive mitigation of blood loss is essential.3 We demonstrate the resection technique in a 40-year-old patient who consented to surgery. The image at 1:30, © Ossama Al-Mefty, is used with permission.

A model to determine soiling, shading and thermal losses from PV yield data

Abstract Apart from being a clean source of energy, photovoltaic (PV) power plants are also a source of income generation for its investors and lenders. Therefore, mitigation of system losses is crucial for economic operation of PV plants. Combined losses due to soiling, shading and temperature in PV plants go as high as 50%. Much of these losses are unaccounted initially, which can jeopardize the economic viability of PV projects. This paper aims to provide a model to determine losses due to soiling, shading and temperature using quantities like irradiance, cell temperature, DC power and current, which are readily available in PV yield data captured by the remote monitoring system, without involving any additional sensors or equipment. In this study, soiling, shading and thermal losses were calculated using PV yield data obtained from a 30-kWp PV plant located in Kharagpur, India. The results showed soiling and shading losses as high as 25.7% and 9.7%, respectively, in the month of December. Soiling loss was verified by measuring transmittance loss of coupon glasses installed in the vicinity of the plant. Shading loss was verified by shadow simulation using an architectural tool (SketchUp). Array thermal loss obtained using the proposed methodology was found to be in line with the estimated value obtained from PVsyst simulation. Additionally, using time-series data, the energy losses corresponding to soiling, shading and temperature effects were calculated by a numerical-integration technique. The monetary loss due to these energy losses thus obtained provides criteria for deciding when to mitigate the sources of these losses.

Organic amendments facilitate soil carbon sequestration via organic carbon accumulation and mitigation of inorganic carbon loss

AbstractBoth soil organic carbon (SOC) and soil inorganic carbon (SIC) are important carbon reservoirs involved in the global carbon cycle. Fertilization especially organic amendments can increase SOC sequestration, while nitrogen fertilization‐induced soil acidification leads to significant SIC loss in alkline soil. How fertilization changes SIC and SOC via altering abiotic and biotic properties remains unclear. Here, we investigated the effects of mineral fertilizer with/without organic amendments (manure, straw, green manure) on SIC and SOC in bulk soil and particle‐size fractions, as well as their interrelationship based on a 38‐year field trial. Results showed that compared to the unfertilized soil, mineral fertilization significantly decreased SIC by 13.38%–15.69%, primarily due to decreased soil pH. However, mineral nitrogen plus manure (NM) largely increased SIC by 26.55%, likely resulting from the reprecipitated by Ca2+ and/or Mg2+ compensation. Mineral nitrogen plus manure and straw (NM, NS) increased SOC by 11.12%–100.35%. For bulk soil and particle‐size fractions >0.25 mm, SIC content was positively correlated with SOC. Random forest model revealed that SOC was regulated by soil nutrients (total nitrogen [TN], Olsen‐P), microbial biomass and β‐1,4‐N‐acetyl‐glucosaminidase. The change in SIC was directly regulated by soil Mg2+, and indirectly by soil nutrients (e.g., TN, Olsen‐P) which affected crop‐derived C input. Our findings suggested that organic manure amendments can facilitate SOC accumulation and mitigate SIC loss by occluded more SIC in large soil particles. The results are of fundamental significance for understanding the role of optimal manure application played in SOC sequestration and SIC accumulation.

Investigation on shock-induced separation loss mitigation method considering radial equilibrium in a transonic compressor rotor

AbstractA shock-induced separation loss reduction method, using local blade suction surface shape modification (smooth ramp structure) with constant adverse pressure gradient with the consideration of radial equilibrium effect to split a single shock foot into multiple weaker shock wave configuration, is investigated on the NASA Rotor 37 for promoting aerodynamic performance of a transonic compressor rotor. Numerical investigation on baseline blade and improved one with blade modification on suction side has been conducted employing the Reynolds-averaged Navier–Stokes method to reveal flow physics of ramp structure. The results indicate that the passage shock foot of baseline is replaced with a family of compression waves and a weaker shock foot generating moderate adverse pressure gradient on ramp profile, which is beneficial for mitigating the shock foot and shrinking flow separation region as well. In addition, the radial secondary flow of low-momentum fluids within boundary layer is decreased significantly in the region of passage shock-wave/boundary-layer interaction on blade suction side, which mitigates the mass flow and mixing intensity of tip leakage flow. With the reduction of flow separation loss induced by passage shock, the adiabatic efficiency and total pressure ratio of improved rotor are superior to baseline model. This study herein implies a potential application of ramp profile in design method of transonic and supersonic compressors.

Architected cellular particles to mitigate asphalt stone loss

This paper aims to quantify stone loss mitigation due to the action of architected cellular particles that can absorb impact energy. The architected cellular particles presented in this paper are additives for asphalt that have been designed to absorb impact energy through an internal porous structure filled with a bitumen-compatible liquid that controls their strength. The experimental programme is divided into four phases: Cellular particle manufacturing and morphological analysis; optimisation of asphalt mixture performance by selecting the cellular particle content based on mass loss, rutting and skid resistance testing; study of mass loss with varying compaction energy and asphalt gradation and microstructural and energy absorption analysis. It was concluded that (i) the asphalt’s mass loss linearly decreased as the cellular particle content was increased, (ii) up to 1% of architected cellular particle content by total weight of the mixture reduced mass loss without producing adverse effects in the asphalt, (iii) architected cellular particles deformed during testing, absorbing the impact load energy.